Settle on a start island fast
When starting with the flagship you can choose which island to settle. You want to choose an island with the potato and wheat fertility that also has a decent size, a so called start islands. Each world will generate with 4 such islands, if you spot one, its most likely the best to just settle. Dont waste too much time looking for the perfect island, because if there was a better start island it is likely already taken by an opponent, once you get there.
Do not lock yourself.
Use your starting wood to have both a market place and some houses. If you built houses without a market, they will decay soon, kicking off a vicious cycle. No houses => No workforce => No wood => No houses. In worst case you are locked.
Use start fish
When starting with a trading post, you start also with 20 fish. So it is not necessary to build a fishing hut right away. As long as you have fish in storage, you better invest your wood in houses.
Do exploration
When starting with a flagship, you have the opportunity to immediately start exploring. Try to find the neutral traders, and take quests to get valueable rewards. Thanks to the flagship, you are also equipped to even do early escort quests. More about map exploration in the section below.
Overclock everything
Until the police station is unlocked, no strikes can break out. So change the working conditions to maximum overclocking everywhere in the early game.
Keep 10000$ at hand
When starting with a trading post, you will need to get a shipyard as fast as possible. So keep 10000$ at hand to be able to buy the shipyard right away when it becomes available.